In the past, processes and apparatus have been developed which apply a liquid photocurable polymer to a support surface, said apparatus providing means for leveling the applied composition to provide a substantially uniform thickness of composition over the support surface. U.S. Pat. No. 3,837,887 to Akamatsu, et al discloses apparatus which supplies a predetermined quantity of liquid resin in one load on the support surface and doctors said resin while simultaneously pressing a plastic backing sheet into the doctored surface of the polymer. Akamatsu, et al disclose apparatus which dumps in one load photopolymer on the support surface, the flow rate of said photopolymer varying depending upon the viscosity of the photopolymer and the depth of the photopolymer as it flows from the bucket. It can be seen that the flow rate of the photopolymer initially after rotation of the bucket will be greater than the flow rate at the point where the bucket has substantially traversed the length of the support surface. This pressure differential in the photopolymer becomes a critical difficulty when making thick plates or when traversing long distances, i.e., the thickness of the plate can vary from thick to thin as the assembly traverses the plate. The only other attempt at solving this problem is that shown in U.S. Pat. No. 3,751,164 to Miller, et al, which discloses a constant pressure dispensing manifold having nozzles to dispense at a uniform rate. The Miller, et al approach is far more complicated, expensive and difficult to maintain than the instant novel approach. The instant invention is an improvement over the Akamatsu, et al apparatus. The instant invention provides apparatus to prepare a smooth and precisely planer surface by metering the amount of photopolymer needed and doctoring the same independent of viscosities or depth of the photopolymer.
U.S. Pat. No. 3,848,998 Yonekura, et al discloses apparatus having a movable carriage to produce a plate of predetermined unvariable thickness. The instant invention provides apparatus which may vary the flow of photopolymer and which is adjustable in height to produce plates of varying thickness. Specifically, the instant invention is an improvment over Yonekura, et al in that the instant invention utilizes the combination of the variable flow rate applicator, a variable thickness shim on which the carriage moves, the preset thickness of said shim corresponding to the thickness of the printing plate desired and an adjustable gear means which drives said carriage.